A senior Earth scientist divulges some little known discoveries, and how they may affect Earth's climate.

Stacey pointed out to us that a planet revolving about the Sun in its “Keplerian” elliptical orbit delivered no energetic jolt to the Sun's photosphere, such as might explain the episodic growth of sunspots. But when two planets are involved, as the faster one passes the slower one, there is briefly a combined gravitational effect that is felt by each of the planets, and more importantly, by the Sun itself. This is not a tide (which is minuscule), but a torque. The outer, gaseous layers of that star have a low viscosity that is susceptible to any change in the angular momentum, just like the Earth atmosphere (in contrast to its hydrosphere and lithosphere).